"Equal access," a mandate imposed by the divestiture of American Telegraph & Telephone Co. ("AT&T"), has facilitated the growth of a large number of private interexchange carriers. To provide long distance service, these carriers must interface with existing "central office" equipment. As is well known in the prior art, a "central office" includes a plurality of switching elements (e.g., a crossbar or step-by-step switch) for connecting an incoming subscriber call from a subscriber line to one of a plurality of outgoing trunks. The central office also includes control circuitry (e.g., originating registers and markers) for receiving and processing called digits from the subscriber and in response thereto controlling the switch element to select an appropriate outgoing trunk to complete the subscriber call.
Existing central office equipment is presently incapable of adequately providing "equal access" and other extended subscriber features to otherwise non-conforming central offices. Accordingly, deregulation and increasing competitive pressures have left central office operators with the option of either replacing older technology or upgrading present equipment in order to meet the demands of both current and future telecommunications requirements. Because replacement or upgrading of existing central office equipment is often cost prohibitive, many operators will not be able to provide extended subscriber features to their subscribers.
Accordingly, there exists a need for enhancing the operating capabilities of a telecommunications switching system to enable existing central offices to offer extended subscriber features, such as equal access, while obviating the replacing or upgrading of existing technology.